1. Field of the Invention
The present invention relates to an apparatus for supporting a sign. More particularly, it relates to a collapsible sign stand which can be quickly and easily set up to support highway warning signs and which can be collapsed into a compact bundle for convenient storage and transportation.
2. Description of the Prior Art
Signs are often temporarily set up to provide motorists with information and warnings, especially during highway construction and repairs and during various emergency situations such as when a road becomes washed-out or when an automobile accident occurs. It is desirable that the supports for these types of outdoor signs be collapsible so that they can be conveniently transported without occupying a large volume of space while also being easily and quickly set up by a workman. Furthermore, the sign stand should be rugged enough to withstand adverse weather and stable enough not to be blown over by the wind or by passing vehicles. Furthermore, it is desirable that the stand be capable of withstanding the rough handling generally associated with equipment used in highway construction.
Known supports for highway stands include the type disclosed in Dalum U.S. Pat. No. 3,591,116, namely a stand constructed generally of a pair of laterally spaced apart vertical legs interconnected at their lower ends by a horizontal bar. A pair of opposed feet extend forwardly and rearwardly from the bottom of each of the two vertical legs to maintain the sign stand in upright position. To enable the sign stand of Dalum to be collapsed, the vertical legs, horizontal bar, and horizontal feet are all pivotally interconnected through the use of spring-loaded joints. Not only is this type of construction expensive, but springs are a common cause of failure, due to fatigue and corrosion, especially when used in outdoor applications. Furthermore, the four horizontal feet of this type of stand cannot properly support the stand if the underlying ground is uneven.
A stand which permits a highway sign to swing fore and aft is disclosed by Dicke U.S. Pat. No. 3,677,511. This stand is constructed of a stationary A-frame which resembles a common sawhorse. A swinging subframe is pivotally mounted between the legs of the A-frame, which subframe includes an upwardly extendable mast for supporting the upper end of a sign. Extension springs are interconnected between the A-frame and swinging subframe to maintain the subframe and mast nominally vertical. This particular sign stand construction, requiring many components, is not only expensive to construct, but also results in a very heavy frame which is difficult for a single workman to handle. Furthermore, this particular sign stand cannot be collapsed in the compact manner of the present invention.
Carpenter U.S. Pat. No. 2,995,847 also concerns a swinging sign stand which incorporates a stationary A-frame resembling a sawhorse. However, the swinging portion of the sign stand of Carpenter does not include an upwardly extendable mast nor extension springs which interconnect the swinging and stationary portions of the frame to maintain the sign in nominally vertical position.
Various types of three-legged supporting devices are also known. One such device is illustrated in FIGS. 1-3 by Proctor U.S. Pat. No. 1,764,868 which involves a stand for supporting harvested flax and grains in the shape of a rick or stack for drying. The stand of Proctor is constructed of three straight legs which are pivotally interconnected at their upper ends to form a tripod. However, to permit the legs to be properly spread out and to be collapsed in a more compact manner, the interconnecting bolt must be so loose that the stand would tend to tip over in the blowing wind. Thus, either triangular hoops to surround the three legs, or, alternatively, horizontal cross bars to interconnect the legs, are provided to stabilize the three legs.
A three-legged device for supporting cameras and surveying instruments is disclosed by Mills U.S. Pat. No. 3,114,529. Each of the three legs has a perpendicularly disposed disc attached to its upper end portion and wedge-shaped spacers are sandwiched between adjacent leg discs. The three legs and two spacers are simultaneously pivotable about a bent bolt which extends through central holes provided in each leg disc and each spacer. A wing nut is provided to engage the threaded end of the bolt to clamp the three leg discs and two spacers together in selected positions. As apparent, this particular type of supporting device not only requires precisely manufactured components but also is limited in its ability to support loads by the amount of clamping force which can be generated by tightening the wing nut. Furthermore, exposure to the weather will cause corrosion in the threads of the bolt making it difficult to tighten and loosen the wing nut.
Also of interest in the field of supporting devices are Macke, Jr. U.S. Pat. No. 377,629, and Rapfogel U.S. Pat. No. 356,532, both of which involve foldable music stands. Both stands include a back rest for supporting sheet music constructed of links pivotally interconnected in the form of "lazy tongs". A rearwardly extending brace is pivotally interconnected to an upper portion of the back rest for maintaining said back support in upright position. These two music stands also include members extending horizontally from a bottom portion of the back rest for supporting the bottom edge of the sheet music. While these types of stands may be adequate for supporting lightweight sheet music, they are not rugged enough to support large, heavy highway signs.